Seminar "An update on K41 vs K62" by Prof. Robert Antonia

[Speaker]

Prof. Robert Antonia

Emeritus Professor

Faculty of Engineering and Built Environment (Mechanical Engineering)

The University of Newcastle, Australia

[Abstract]

Although Kolmogorov’s (1962) correction (K62) to his 1941 theory (K41) has been embraced by an overwhelming majority of turbulence researchers, our recent work suggests that there are no valid reasons for abandoning K41. In particular, analytical considerations, based on the NS equations, which take into account the finite Reynolds number effect, together with the available experimental and numerical data, seem to confirm a tendency towards the simple and elegant predictions of K41 as the Reynolds number increases. This is especially true when the focus is on length scales which lie in the dissipative range. Since K62 is predicated on the idea that large scales continue to affect small scales, it cannot be reconciled with the 4/5 law, a result that is exact when the Reynolds number approaches infinity. Further, the so-called ‘anomalous’ behaviour in the inertial range ( strictly a ‘scaling’ range) of the power-law exponent for the longitudinal velocity structure function can only be considered as ‘fictitious’ when the Reynolds number is finite.